Hair as nidus for ureteral calculus formation: case report.

A 52-year-old man with a significant history of nephrolithiasis was found to have a calcium oxalate dihydrate ureteral calculus that apparently formed on a hair. This nidus may have been introduced during previous instrumentation, perhaps on the tip of the ureteroscope, laser fiber, or even during the placement of a ureteral stent.